Carbon aerogels are porous materials with high porosity. Due to their high electrical conductivity and large specific surface area, carbon aerogels may be used in high-performance electrode materials, energy storage devices, harmful substance adsorbents, capacitive deionization-based water purification processes, seawater desalination processes, ion exchange-based waste water treatment processes, and the like. Such carbon aerogels may be obtained from heat treatment of organic aerogels. In general, starting materials for preparing the organic aerogels include resorcinol-formaldehyde, polyacrylonitrile (PAN) and polyurethane (PU). In the case of most existing organic aerogels, an adequate amount of catalyst is added to aqueous solution of the above organic materials, followed by heating, to form the gels over a period of several days or more. Further, the gels obtained from the above method are subjected to supercritical drying, and thus require an additional step of substituting the solvent in the gels with another solvent, such as acetone, suitable for supercritical drying using carbon dioxide. However, these processes are expensive, energy and time consuming, and also needs sophisticated instruments. Thus, simple and energy efficient methods to prepare carbon aerogels, especially from available biomaterials, are desired.